A high power MOS Field Effect Transistor (MOSFET), which is a unipolar device, may have relatively high input impedance compared to a bipolar transistor, so that it can have a great power gain and simple gate driver ICs. The high power MOSFET also has an advantage of no substantial time delay due to minority carrier accumulation and/or recombination when the device is turned-off. Accordingly, use of such a MOSFET has recently increased in various applications including, for example, production of a switching mode power supply, (open) lamp regulation, production of a motor driver IC, etc. Such a power MOSFET may include, for example, a double diffused MOSFET (DMOSFET) structure which uses a planar diffusion technique. Among high voltage semiconductor devices, a lateral diffusion MOS (LDMOS) having a specific structure suitable for high voltage applications, in which a channel region and a drain electrode are separated from each other by interposing a drift region therebetween and are controlled by a gate electrode, is an example of a DMOSFET.
FIG. 1 is a cross-sectional view illustrating each transistor of a low voltage (LV) MOS gate driver and a high voltage (HV) MOS gate driver. Referring to FIG. 1, the gate driver may include LV PMOS, LV NMOS, HV NMOS and/or HV PMOS. In manufacturing such a gate driver, a channel ion implantation for targeting threshold voltages of HV NMOS and HV PMOS transistors needs an ion implantation mask so as to separately control the above HV NMOS and HV PMOS transistors, thereby causing an increase in production costs of the gate driver.